Portal:Fallacies
Portal maintenance status: (October 2018)
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Introduction
A fallacy is the use of invalid or otherwise faulty reasoning, or "wrong moves" in the construction of an argument. A fallacious argument may be deceptive by appearing to be better than it really is. Some fallacies are committed intentionally to manipulate or persuade by deception, while others are committed unintentionally due to carelessness or ignorance. The soundness of legal arguments depends on the context in which the arguments are made.
Fallacies are commonly divided into "formal" and "informal". A formal fallacy can be expressed neatly in a standard system of logic, such as propositional logic, while an informal fallacy originates in an error in reasoning other than an improper logical form. Arguments containing informal fallacies may be formally valid, but still fallacious.
Selected general articles
- Circular reasoning (Latin: circulus in probando, "circle in proving"; also known as circular logic) is a logical fallacy in which the reasoner begins with what they are trying to end with. The components of a circular argument are often logically valid because if the premises are true, the conclusion must be true. Circular reasoning is not a formal logical fallacy but a pragmatic defect in an argument whereby the premises are just as much in need of proof or evidence as the conclusion, and as a consequence the argument fails to persuade. Other ways to express this are that there is no reason to accept the premises unless one already believes the conclusion, or that the premises provide no independent ground or evidence for the conclusion. Begging the question is closely related to circular reasoning, and in modern usage the two generally refer to the same thing.
Circular reasoning is often of the form: "A is true because B is true; B is true because A is true." Circularity can be difficult to detect if it involves a longer chain of propositions.
Academic Douglas Walton used the following example of a fallacious circular argument:
:Wellington is in New Zealand.
:Therefore, Wellington is in New Zealand. Read more... - An argumentum ad crumenam argument, also known as an argument to the purse, is the informal fallacy of concluding that a statement is correct because the speaker is rich (or that a statement is incorrect because the speaker is poor).
The opposite is the argumentum ad lazarum. Read more... - Moving the goalposts (or shifting the goalposts) is a metaphor, derived from goal-based sports, that means to change the criterion (goal) of a process or competition while it is still in progress, in such a way that the new goal offers one side an intentional advantage or disadvantage. Read more...
- The fallacy of composition arises when one infers that something is true of the whole from the fact that it is true of some part of the whole (or even of every proper part). For example: "This wheel is made of rubber, therefore the vehicle to which it is a part is also made of rubber." This is fallacious, because vehicles are made with a variety of parts, many of which may not be made of rubber.
This fallacy is often confused with the fallacy of hasty generalization, in which an unwarranted inference is made from a statement about a sample to a statement about the population from which it is drawn. Read more... - Circumstantial ad hominem points out that someone is in circumstances such that they are disposed to take a particular position. It constitutes an attack on the bias of a source. This is fallacious because a disposition to make a certain argument does not make the argument invalid; this overlaps with the genetic fallacy (an argument that a claim is incorrect due to its source).
The circumstantial fallacy does not apply where the source is taking a position by using a logical argument based solely on premises that are generally accepted. Where the source seeks to convince an audience of the truth of a premise by a claim of authority or by personal observation, observation of their circumstances may reduce the evidentiary weight of the claims, sometimes to zero. Read more... - False equivalence is a logical fallacy in which two completely opposing arguments appear to be logically equivalent when in fact they are not. This fallacy is categorized as a fallacy of inconsistency. Read more...
- An association fallacy is an informal inductive fallacy of the hasty-generalization or red-herring type and which asserts, by irrelevant association and often by appeal to emotion, that qualities of one thing are inherently qualities of another. Two types of association fallacies are sometimes referred to as guilt by association and honor by association. Read more...
- An overwhelming exception is an informal fallacy of generalization. It is a generalization that is accurate, but comes with one or more qualifications which eliminate so many cases that what remains is much less impressive than the initial statement might have led one to believe. Read more...
When Charles Darwin (pictured) published On the Origin of Species in 1859, some commentators pooh-poohed his theories as the "harmless dream of a man napping".
A pooh-pooh (also styled as poo-poo) is a fallacy in informal logic that consists of dismissing an argument as being unworthy of serious consideration. Scholars generally characterize the fallacy as a rhetorical device in which the speaker ridicules an argument without responding to the substance of the argument. Read more...- In political discourse, if-by-whiskey is a relativist fallacy in which the speaker's position is contingent on the listener's opinion. An if-by-whiskey argument implemented through doublespeak appears to affirm both sides of an issue, and agrees with whichever side the listener supports, in effect taking a position without taking a position. The statement typically uses words with strongly positive or negative connotations (e.g., terrorist as negative and freedom fighter as positive). Read more...
- False attribution can refer to:
- Misattribution in general, when a quotation or work is accidentally, traditionally, or based on bad information attributed to the wrong person or group
- A specific fallacy where an advocate appeals to an irrelevant, unqualified, unidentified, biased, or fabricated source in support of an argument.
- The courtier's reply is an alleged type of logical fallacy, coined by American biologist PZ Myers, in which a respondent to criticism claims that the critic lacks sufficient knowledge, credentials, or training to pose any sort of criticism whatsoever. It may be considered a form of argument from authority.
A key element of a courtier's reply, which distinguishes it from an otherwise valid response that incidentally points out the critic's lack of established authority on the topic, is that the respondent never shows how the work of these overlooked experts invalidates the arguments that were advanced by the critic. Read more... - The definist fallacy (sometimes Socratic fallacy) is a logical fallacy, coined by William Frankena in 1939, that involves the definition of one property in terms of another. Read more...
- Survivorship bias or survival bias is the logical error of concentrating on the people or things that made it past some selection process and overlooking those that did not, typically because of their lack of visibility. This can lead to false conclusions in several different ways. It is a form of selection bias.
Survivorship bias can lead to overly optimistic beliefs because failures are ignored, such as when companies that no longer exist are excluded from analyses of financial performance. It can also lead to the false belief that the successes in a group have some special property, rather than just coincidence (correlation proves causality). For example, if three of the five students with the best college grades went to the same high school, that can lead one to believe that the high school must offer an excellent education. This could be true, but the question cannot be answered without looking at the grades of all the other students from that high school, not just the ones who "survived" the top-five selection process. Read more... - Appeal to motive is a pattern of argument which consists in challenging a thesis by calling into question the motives of its proposer. It can be considered as a special case of the ad hominem circumstantial argument. As such, this type of argument may be an informal fallacy.
A common feature of appeals to motive is that only the possibility of a motive (however small) is shown, without showing the motive actually existed or, if the motive did exist, that the motive played a role in forming the argument and its conclusion. Indeed, it is often assumed that the mere possibility of motive is evidence enough. Read more... - The historical fallacy is a logical fallacy originally described by philosopher John Dewey in The Psychological Review in 1896. Most simply put, the fallacy occurs when a person reads into a process the results that occur only because of that process. Dewey writes:
:"A set of considerations which hold good only because of a completed process, is read into the content of the process which conditions this completed result. A state of things characterizing an outcome is regarded as a true description of the events which led up to this outcome; when, as a matter of fact, if this outcome had already been in existence, there would have been no necessity for the process." Read more... - A slippery slope argument (SSA), in logic, critical thinking, political rhetoric, and caselaw, is a consequentialist logical device in which a party asserts that a relatively small first step leads to a chain of related events culminating in some significant (usually negative) effect. The core of the slippery slope argument is that a specific decision under debate is likely to result in unintended consequences. The strength of such an argument depends on the warrant, i.e. whether or not one can demonstrate a process that leads to the significant effect. This type of argument is sometimes used as a form of fear mongering, in which the probable consequences of a given action are exaggerated in an attempt to scare the audience. The fallacious sense of "slippery slope" is often used synonymously with continuum fallacy, in that it ignores the possibility of middle ground and assumes a discrete transition from category A to category B. In a non-fallacious sense, including use as a legal principle, a middle-ground possibility is acknowledged, and reasoning is provided for the likelihood of the predicted outcome.
Other idioms for the slippery slope argument are the thin end/edge of the wedge and the camel's nose in the tent. Read more... - The prosecutor's fallacy is a fallacy of statistical reasoning, typically used by the prosecution to argue for the guilt of a defendant during a criminal trial. Although it is named after prosecutors, it is not specific to them, and some variants of the fallacy can be used by defense lawyers arguing for the innocence of their client.
The following demonstrates the fallacy in the context of a prosecutor questioning an expert witness: “the odds of finding this evidence on an innocent man are so small that the jury can safely disregard the possibility that this defendant is innocent”. The fallacy obscures that the odds of a defendant being innocent given said evidence in fact depends on the likely higher prior odds of the defendant being innocent, the explicitly lesser odds of the evidence in the case that he was innocent as mentioned, as well as the underlying cumulative odds of the evidence being on the defendant. Read more... - The furtive fallacy is an informal fallacy of emphasis in which outcomes are asserted to have been caused by the hidden misconduct or wrongdoing by decision makers. Historian David Hackett Fischer identified it as the belief that significant facts of history are necessarily sinister, and that "history itself is a story of causes mostly insidious and results mostly invidious." It is more than a conspiracy theory in that it does not merely consider the possibility of hidden motives and deeds, but insists on them. In its extreme form, the fallacy represents general paranoia.
Fischer identifies several examples of the fallacy, particularly the works of Charles A. Beard. In each case, Fischer shows that historians provided detailed portrayals of historical figures involved in off-record meetings and exhibiting low morals, based on little or no evidence. He notes that the furtive fallacy does not necessarily imply deliberate falsification of history; it can follow from a sincere (but misguided) belief that nothing happens by accident or mistake. Read more...
Begging the question is a logical fallacy that occurs when an argument's premises assume the truth of the conclusion, instead of supporting it. It is a type of circular reasoning and an informal fallacy: an argument that requires that the desired conclusion be true. This often occurs in an indirect way such that the fallacy's presence is hidden, or at least not easily apparent.
The phrase begging the question originated in the 16th century as a mistranslation of the Latin petitio principii, which actually translates to "assuming the initial point". In modern vernacular usage, "begging the question" is frequently used to mean "raising the question" or "dodging the question". In contexts that demand strict adherence to a technical definition of the term, many consider these usages incorrect. Read more...- Magical thinking is a term used in anthropology and psychology, denoting the fallacious attribution of causal relationships between actions and events, with subtle differences in meaning between the two fields. In anthropology, it denotes the attribution of causality between entities grouped with one another (coincidence) or similar to one another.
In psychology, the entities between which a causal relation has to be posited are more strictly delineated; here it denotes the belief that one's thoughts by themselves can bring about effects in the world or that thinking something corresponds with doing it. In both cases, the belief can cause a person to experience fear, seemingly not rationally justifiable to an observer outside the belief system, of performing certain acts or having certain thoughts because of an assumed correlation between doing so and threatening calamities. Read more... - The Roman politician Marcus Tullius Cicero coined the phrase ipse dixit, which translates from the Latin as, "he said it himself"
Ipse dixit (Latin for "he said it himself") is an assertion without proof; or a dogmatic expression of opinion.
The fallacy of defending a proposition by baldly asserting that it is "just how it is" distorts the argument by opting out of it entirely: the claimant declares an issue to be intrinsic, and not changeable. Read more... - The historian's fallacy is an informal fallacy that occurs when one assumes that decision makers of the past viewed events from the same perspective and having the same information as those subsequently analyzing the decision. It is not to be confused with presentism, a mode of historical analysis in which present-day ideas (such as moral standards) are projected into the past.
The idea that a critic can make erroneous interpretations of past works because of knowledge of subsequent events was first articulated by British literary critic Matthew Arnold. In his 1880 essay The Study of Poetry, Arnold wrote: Read more... - The nirvana fallacy is the informal fallacy of comparing actual things with unrealistic, idealized alternatives. It can also refer to the tendency to assume that there is a perfect solution to a particular problem. A closely related concept is the perfect solution fallacy.
By creating a false dichotomy that presents one option which is obviously advantageous—while at the same time being completely implausible—a person using the nirvana fallacy can attack any opposing idea because it is imperfect. Under this fallacy, the choice is not between real world solutions; it is, rather, a choice between one realistic achievable possibility and another unrealistic solution that could in some way be "better". Read more... - An appeal to pity (also called argumentum ad misericordiam, the sob story, or the Galileo argument) is a fallacy in which someone tries to win support for an argument or idea by exploiting his or her opponent's feelings of pity or guilt. It is a specific kind of appeal to emotion. The name "Galileo argument" refers to the scientist's suffering as a result of his house arrest by the Inquisition. Read more...
- An argument from authority, (argumentum ab auctoritate), also called an appeal to authority, or argumentum ad verecundiam is a form of defeasible argument in which a claimed authority's support is used as evidence for an argument's conclusion. It is well known as a fallacy, though it is used in a cogent form when all sides of a discussion agree on the reliability of the authority in the given context. Read more...
- Judgmental language is a subset of red herring fallacies. It employs insulting, compromising or pejorative language to influence the recipient's judgment. Read more...
- A faulty generalization is a conclusion about all or many instances of a phenomenon that has been reached on the basis of just one or just a few instances of that phenomenon. It is an example of jumping to conclusions. For example, we may generalize about all people, or all members of a group, based on what we know about just one or just a few people. If we meet an angry person from a given country X, we may suspect that most people in country X are often angry. If we see only white swans, we may suspect that all swans are white. Faulty generalizations may lead to further incorrect conclusions. We may, for example, conclude that citizens of country X are genetically inferior, or that poverty is generally the fault of the poor.
Expressed in more precise philosophical language, a fallacy of defective induction is a conclusion that has been made on the basis of weak premises. Unlike fallacies of relevance, in fallacies of defective induction, the premises are related to the conclusions yet only weakly buttress the conclusions. A faulty generalization is thus produced. This inductive fallacy is any of several errors of inductive inference. Read more...
Paul Graham's Hierarchy of Disagreement lists ad hominem as the second lowest type of argument in a disagreement.
Ad hominem (Latin for "to the person"), short for argumentum ad hominem, is a fallacious argumentative strategy whereby genuine discussion of the topic at hand is avoided by instead attacking the character, motive, or other attribute of the person making the argument, or persons associated with the argument, rather than attacking the substance of the argument itself. The terms ad mulierem and ad feminam have been used specifically when the person receiving the criticism is female.
However, its original meaning was an argument "calculated to appeal to the person addressed more than to impartial reason". Read more...- An ecological fallacy (or ecological inference fallacy) is a formal fallacy in the interpretation of statistical data where inferences about the nature of individuals are deduced from inferences about the group to which those individuals belong. Ecological fallacy sometimes refers to the fallacy of division, which is not a statistical issue. The four common statistical ecological fallacies are: confusion between ecological correlations and individual correlations, confusion between group average and total average, Simpson's paradox, and confusion between higher average and higher likelihood. Read more...
- The fallacy of the undistributed middle (Lat. non distributio medii) is a formal fallacy that is committed when the middle term in a categorical syllogism is not distributed in either the minor premise or the major premise. It is thus a syllogistic fallacy. Read more...
- The fallacy of four terms (Latin: quaternio terminorum) is the formal fallacy that occurs when a syllogism has four (or more) terms rather than the requisite three. This form of argument is thus invalid. Read more...
Begging the question is a logical fallacy that occurs when an argument's premises assume the truth of the conclusion, instead of supporting it. It is a type of circular reasoning and an informal fallacy: an argument that requires that the desired conclusion be true. This often occurs in an indirect way such that the fallacy's presence is hidden, or at least not easily apparent.
The phrase begging the question originated in the 16th century as a mistranslation of the Latin petitio principii, which actually translates to "assuming the initial point". In modern vernacular usage, "begging the question" is frequently used to mean "raising the question" or "dodging the question". In contexts that demand strict adherence to a technical definition of the term, many consider these usages incorrect. Read more...- Affirming the consequent, sometimes called converse error, fallacy of the converse, or confusion of necessity and sufficiency, is a formal fallacy of taking a true conditional statement (e.g., "If the lamp were broken, then the room would be dark,") and invalidly inferring its converse ("The room is dark, so the lamp is broken,") even though the converse may not be true. This arises when a consequent ("the room would be dark") has one or more other antecedents (for example, "the lamp is not plugged in" or "the lamp is in working order, but is switched off").
Converse errors are common in everyday thinking and communication and can result from, among other causes, communication issues, misconceptions about logic, and failure to consider other causes. Read more... - Argument from fallacy is the formal fallacy of analyzing an argument and inferring that, since it contains a fallacy, its conclusion must be false. It is also called argument to logic (argumentum ad logicam), the fallacy fallacy, the fallacist's fallacy, and the bad reasons fallacy.
Fallacious arguments can arrive at true conclusions, so this is an informal fallacy of relevance. Read more... - A straw man is a common form of argument and is an informal fallacy based on giving the impression of refuting an opponent's argument, while actually refuting an argument that was not presented by that opponent. One who engages in this fallacy is said to be "attacking a straw man."
The typical straw man argument creates the illusion of having completely refuted or defeated an opponent's proposition through the covert replacement of it with a different proposition (i.e., "stand up a straw man") and the subsequent refutation of that false argument ("knock down a straw man") instead of the opponent's proposition. Read more... - The regression (or regressive) fallacy is an informal fallacy. It assumes that something has returned to normal because of corrective actions taken while it was abnormal. This fails to account for natural fluctuations. It is frequently a special kind of the post hoc fallacy. Read more...
- In mathematics and logic, a vacuous truth is a statement that asserts that all members of the empty set have a certain property. For example, the statement "all cell phones in the room are turned off" will be true whenever there are no cell phones in the room. In this case, the statement "all cell phones in the room are turned on" would also be vacuously true, as would the conjunction of the two: "all cell phones in the room are turned on and turned off".
More formally, a relatively well-defined usage refers to a conditional statement with a false antecedent. One example of such a statement is "if Uluru is in France, then the Eiffel Tower is in Bolivia". Such statements are considered vacuous because the fact that the antecedent is false prevents using the statement to infer anything about the truth value of the consequent. They are true because a material conditional is defined to be true when the antecedent is false (regardless of whether the conclusion is true). Read more... - Metaphilosophy is a peer-reviewed academic journal covering metaphilosophy. It is abstracted and indexed by PhilPapers and the Philosopher's Index.
Metaphilosophy was established in 1970 by Terry Bynum and Richard Reese. "Metaphilosophy" was given a working definition in the first issue of the journal as "the investigation of the nature of philosophy, with the central aim of arriving at a satisfactory explanation of the absence of uncontested philosophical claims and arguments." The journal is published by John Wiley & Sons and the editor-in-chief is Armen T. Marsoobian (Southern Connecticut State University). Read more... - The genetic fallacy (also known as the fallacy of origins or fallacy of virtue) is a fallacy of irrelevance that is based solely on someone's or something's history, origin, or source rather than its current meaning or context. This overlooks any difference to be found in the present situation, typically transferring the positive or negative esteem from the earlier context. In other words, a fact is ignored in favor of attacking its source.
The fallacy therefore fails to assess the claim on its merit. The first criterion of a good argument is that the premises must have bearing on the truth or falsity of the claim in question. Genetic accounts of an issue may be true, and they may help illuminate the reasons why the issue has assumed its present form, but they are not conclusive in determining its merits. Read more...
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Informal fallacies | |
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| Equivocation | |
| Question-begging fallacies | |
| Correlative-based fallacies | |
| Illicit transference | |
| Secundum quid (ignoring qualifications) | |
| Faulty generalization | |
| Vagueness / Ambiguity | |
| Questionable cause |
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